User equipment (UE), also known as mobile stations, wireless terminals and/or mobile terminals are enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The communication may be made e.g. between two user equipment units, between a user equipment and a regular telephone and/or between a user equipment and a server via a Radio Access Network (RAN) and possibly one or more core networks.
The user equipment units may further be referred to as mobile telephones, cellular telephones, laptops with wireless capability. The user equipment units in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another user equipment or a server.
The wireless communication system covers a geographical area which is divided into cell areas, with each cell area being served by a network node, or base station e.g. a Radio Base Station (RBS), which in some networks may be referred to as “eNB”, “eNodeB”, “NodeB” or “B node”, depending on the technology and terminology used. The network nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. A cell is the geographical area where radio coverage is provided by the network node/base station at a base station site. One base station, situated on the base station site, may serve one or several cells. The network nodes communicate over the air interface operating on radio frequencies with the user equipment units within range of the respective network node.
In some radio access networks, several network nodes may be connected, e.g. by landlines or microwave, to a Radio Network Controller (RNC) e.g. in Universal Mobile Telecommunications System (UMTS). The RNC, also sometimes termed a Base Station Controller (BSC) e.g. in GSM, may supervise and coordinate various activities of the plural network nodes connected thereto. GSM is an abbreviation for Global System for Mobile Communications (originally: Groupe Spécial Mobile).
In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), network nodes, or base stations, which may be referred to as eNodeBs or even eNBs, may be connected to a gateway e.g. a radio access gateway, to one or more core networks.
UMTS is a third generation mobile communication system, which evolved from the GSM, and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA) access technology. UMTS Terrestrial Radio Access Network (UTRAN) is essentially a radio access network using wideband code division multiple access for user equipment units. The 3GPP has undertaken to evolve further the UTRAN and GSM based radio access network technologies.
The 3GPP is responsible for the standardization of GSM, UMTS, LTE and LTE-Advanced. LTE is a technology for realizing high-speed packet-based communication that may reach high data rates both in the downlink and in the uplink, and is thought of as a next generation mobile communication system relative UMTS.
In the present context, the expressions downlink, downstream link or forward link may be used for the transmission path from the network node to the user equipment. The expression uplink, upstream link or reverse link may be used for the transmission path in the opposite direction i.e. from the user equipment to the network node.
In a communication system based on LTE, there are a number of idle mode parameters such as Qrxlevmin and Qhyst, that control the circumstances under which a user equipment shall camp on an LTE cell. In effect these parameters decide the size of the LTE cell at cell selection and cell reselection in idle mode. These parameters may herein be referred to as cell size parameters, and may for example set the lowest received signal strength, as perceived by a user equipment, for which the user equipment is allowed to utilize an LTE cell. Such cell size parameters may further be associated with a quality measurement. Thus, a quality threshold value may be set, which represent the lowest measured signal quality for which the user equipment may be allowed to camp on the LTE cell.
The idle mode parameters are set by the operator and this activity requires a cell planning effort. For example, the parameters may be set and/or adjusted based on manual signal strength measurements, i.e. the operator may drive around in a physically vehicle, make measurements on signal strength and adjust the parameters, which require manual work and takes time. Once set, the parameters are distributed to the user equipments via System Information.
It has been noticed that there are many timeouts of the Radio Resource Control (RRC) Connection Setup procedure. These timeouts may have occurred due to faulty tuned idle mode parameters, i.e. user equipment that should be camping on another cell, e.g. based on another access technology such as CDMA2000 cell, WCDMA cell, GSM cell etc was actually camping on the LTE cell. When attempting access to the LTE cell the RRC Connection Setup procedure may fail since the coverage at the cell border was in reality too poor.